Microservices tenets

Abstract

Some microservices proponents claim that microservices form a new architectural style; in contrast, advocates of service-oriented architecture (SOA) argue that microservices merely are an implementation approach to SOA. This overview and vision paper first reviews popular introductions to microservices to identify microservices tenets. It then compares two microservices definitions and contrasts them with SOA principles and patterns. This analysis confirms that microservices indeed can be seen as a development- and deployment-level variant of SOA; such microservices implementations have the potential to overcome the deficiencies of earlier approaches to SOA realizations by employing modern software engineering paradigms and Web technologies such as domain-driven design, RESTful HTTP, IDEAL cloud application architectures, polyglot persistence, lightweight containers, a continuous DevOps approach to service delivery, and comprehensive but lean fault management. However, these paradigms and technologies also cause a number of additional design choices to be made and create new options for many “distribution classics” type of architectural decisions. As a result, the cognitive load for (micro-)services architects increases, as well as the design, testing and maintenance efforts that are required to benefit from an adoption of microservices. To initiate and frame the buildup of architectural knowledge supporting microservices projects, this paper compiles related practitioner questions; it also derives research topics from these questions. The paper concludes with a summarizing position statement: microservices constitute one particular implementation approach to SOA (service development and deployment).

Notes

Acknowledgements

The author would like to thank Jonas Biedermann, Simon Brown, Wolfgang Giersche, Gregor Hohpe, Hansjörg Huser, Oliver Kopp, Frank Leymann, Daniel Lübke, Cesare Pautasso, Gerald Reif, Mirko Stocker, the attendees of the SEI SATURN 2015 workshop on microservices as well as the anonymous peer reviewers of and paper presentation/poster session attendees at SummerSoC 2016 for inspiring discussions and/or thoughtful comments on earlier versions of this article. The author would also like to thank James Lewis for the constructive and inspiring discussion following his ICWE 2016 keynote, which confirmed the SOA vs. microservices positioning presented in this paper, which had been accepted for publication previously.